Through the use of a new technology, we will study cavitation bioeffects. We plan to do this by using an in vivo resonant bubble detector to determine thresholds for resonant bubble formation in response to spatial peak, time averaged intensities with continuous wave ultrasound, and intensity time thresholds with pulsed ultrasound. Next we will evaluate the effects of resonant bubbles on the blood coagulation system, particularly platelet functon. We will also investigate the effects of turbulent blood flow and ultrasonic "contract" media i.e. injected bubbles) on these threshold associated parameters. To accomplish these aims, we have combined the talents of a physicist with considerable experience in ultrasonics, a biophysicist with considerable experience in the adverse effects of ultrasonic irradiation on biological tissues both in vitro and in vivo, and a veterinary physiologist with considerable experience in hemodynamics and the preparation and use of animal models. Our long term goals are to quantitatively evaluate cavitation bioeffects in patients. Although we do not expect to find that ultrasonic irradiation is particularly hazardous, any information obtained concerning risk should prove beneficial to medical practitioners concerned with patient safety during exposure to ultrasonic devices. It is prudent that we consider possible harmful effects in an appropriate animal model.